Spaceborne differential optical absorption spectrometer has three working modes: earth observation, spectrum calibration with solar, and halogen light detector self-inspection with halogen light. Therefore, three corresponding optical systems are needed. To make full use of the optical path, the three optical systems share part of the optical path. So, the solar baffle moving parts, the optical road switching moving parts, and the diffuser plate calibration moving parts are designed to switch the three optical paths. The three moving parts were tested for life, and the whole machine was tested by thermal vacuum and heat balance. The experimental results show that the moving parts are operating normally, and the moving parts meet the life requirements and environmental adaptation requirements.